Re: [RFC/RFA] find_pc_sect_psymtab(): symbol table not always complete

Daniel Jacobowitz
2003-12-02T16:15:11Z

On Wed, Nov 19, 2003 at 04:23:59PM -0800, Joel Brobecker wrote:
> > > 2003-11-19 J. Brobecker <brobecker@gnat.com>
> > >
> > > * symtab.c (find_pc_sect_psymtab): Refine the search for the
> > > partial symtab corresponding to the given PC address, taking
> > > into account the fact that the symbol table might be incomplete.
> >
> > FWIW, this looks good to me, but I'd like another comment on the new
> > test to the effect of, the find_pc_sect_psymtab call will always return
> > the closest symbol below pc in tpst. Threw me for a moment how you
> > were just checking for the highest valued symbol.
>
> Thanks for your feedback Daniel. I agree on that a comment is useful.
> Here is a revised version of the patch. Is it better?

This looks great to me. It'll need to be approved by the symtab
maintainers.

> Index: symtab.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/symtab.c,v
> retrieving revision 1.122
> diff -u -p -r1.122 symtab.c
> --- symtab.c 8 Nov 2003 00:13:03 -0000 1.122
> +++ symtab.c 20 Nov 2003 00:21:30 -0000
> @@ -698,6 +698,8 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
> if (pc >= pst->textlow && pc < pst->texthigh)
> {
> struct partial_symtab *tpst;
> + struct partial_symtab *best_pst = pst;
> + struct partial_symbol *best_psym = NULL;
>
> /* An objfile that has its functions reordered might have
> many partial symbol tables containing the PC, but
> @@ -710,6 +712,11 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
> if (msymbol == NULL)
> return (pst);
>
> + /* The code range of partial symtabs sometimes overlap, so
> + we need to check all partial symtabs and find the one that
> + fits better for the given PC address. We select the partial
> + symtab that contains a symbol which address is closest to
> + the PC address. */
> for (tpst = pst; tpst != NULL; tpst = tpst->next)
> {
> if (pc >= tpst->textlow && pc < tpst->texthigh)
> @@ -721,9 +728,24 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
> && SYMBOL_VALUE_ADDRESS (p)
> == SYMBOL_VALUE_ADDRESS (msymbol))
> return (tpst);
> + if (p != NULL)
> + {
> + /* We found a symbol in this partial symtab which
> + matches PC, check whether it is closer than our
> + current BEST_PSYM. Since this symbol address is
> + necessarily lower or equal to PC, the symbol closer
> + to PC is the symbol which address is the highest. */
> + if (best_psym == NULL
> + || SYMBOL_VALUE_ADDRESS (p)
> + > SYMBOL_VALUE_ADDRESS (best_psym))
> + {
> + best_psym = p;
> + best_pst = tpst;
> + }
> + }
> }
> }
> - return (pst);
> + return best_pst;
> }
> }
> return (NULL);

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer